Preheat oven to 375 degrees and lightly grease a baking sheet. In a small bowl, whisk together oil, garlic, Dijon mustard, agave, salt, and pepper. In a medium bowl, toss Brussels sprouts with marinade.

Place Brussels sprouts in a single layer on baking sheet and roast for 25 to 30 minutes until leaves are crispy and sprouts are golden brown. Serve immediately.